Positional Hum & Mu Shield

Alan,
One thing that can help with reducing positional hum is placing Mu
shield around your tube. This can be in the form of a small cylinder
that goes around the tube neck to complete lining of the tube cover
and a Mu shield cover under the tube.
You can contact Dave Grilli at Mu Shield.
Phone 603-666-4433
Fax 603-666-4013
They will make up any piece you need.
David Warner Crawford Communications